2. Field of the Invention
The present invention generally relates to paper or currency handling machines. The invention relates more particularly to a method and apparatus for efficient feeding of stacked currency bills and the like in single file, from a hopper to a downstream stacker along a system transport path, with reduced possibility of double feeding and chaining errors.
2. Description of the Related Art
Numerous techniques and apparatus have been developed and are commercially available for addressing a wide range of automated currency handling applications. Advanced systems of this type are capable of identifying and discriminating between and automatically counting multiple currency denominations, and typically employ some form of optical sensing for discriminating between different currency denominations.
In such currency handling apparatus, currency bills to be discriminated according to denomination and counted are accepted within an input bin or hopper defined by a plurality of enclosing vertically disposed walls in combination with a generally sloping bottom surface, so that the enclosure is adapted to support a stack of currency bills positioned therein. From the input bin, currency bills are moved along a multi-sectional transport path through a currency discrimination station where test bills are identified according to denomination and counted before being relayed to a stacker where processed bills are stacked for subsequent removal.
An exemplary currency discrimination and counting apparatus of this type is described in detail in Raterman, et al. U.S. patent application Ser. No. 07/475,111, filed Feb. 5, 1990, entitled Method and Apparatus For Currency Discrimination and Counting, assigned to Cummins-Allison Corporation, which is also the Assignee of all patent rights related to the present application. The disclosure in that application is incorporated herein by reference for purposes of facilitating the understanding of the mechanical arrangement according to which currency bills stacked in the input bin are moved along a multi-sectional transport path.
Such a bill transport path typically includes an input path where bills are moved along a fast direction in a substantially flat position, a curved guideway where bills are accepted from the input path and guided in such a way as to change the direction of travel to a second different direction, and an output path where the bills are moved in a flat position along the second different direction across currency discrimination means located downstream of the curved guideway.
In the currency handling and counting apparatus described in the above-identified Raterman, et al. application, as well as in other apparatus of this type, it is important to provide means for picking up or "stripping" currency bills, one at a time, from bills that are stacked in the input bin of the apparatus. Toward realizing this "stripping" action, at least one rotationally driven feed roller is provided within the input bin area in the form of an eccentric roller at least a part of the periphery of which is provided with a relatively high friction-bearing surface. In operation, the friction-bearing surface on the feed roller engages the bottom bill of a stack of bills in the input bin as the roller rotates; this initiates the advancement of the bottom bill along the transport path, and the eccentric surface of the feed roller essentially "jogs" the bill stack once per revolution so as to agitate and loosen the bottom currency bill within the stack, thereby facilitating the advancement of the bottom bill along the feed direction.
Typically, the feed roller action is supplemented by one or more drum or capstan rollers disposed downstream of the feed roller and which also is rotationally driven and includes a periphery having a friction-bearing surface. Rotational movement of the drum roller induces additional frictional contact with bills which have presumably already been "jogged" by the earlier action of the feed roller.
With arrangements of this type, active contact between the drum rollers and a currency bill which is jogged by the feed roller and is in the process of being advanced frictionally by the drum rollers is insured by the provision of at least one picker roller for exerting a consistent downward force onto the leading edges of the currency bills stationed within the input bill. The picker rollers are pivotally mounted in a freewheeling fashion and, in the absence of currency bills in contact with the drum roller, bear down upon the drum roller and, accordingly, are induced into counter-rotation therewith.
When currency bills are present and are in contact with the drum roller, the picker rollers bear down into contact with the leading edges of the currency bills and exert a direct downward force on the bills since the rotational movement of rollers is inhibited. When a substantially large stack of bills is present, the result is that the advancing action brought about by the rotational movement of the drum roller is accentuated, thereby facilitating the stripping away of a single currency bill at a time from the bill stack.
While the above-described feed arrangement functions effectively with large stacks of bills, the feeding action of the picker rollers tends to inhibit the "stripping" action when a relatively small stack of bills, typically about 20 to 30 bills, is fed from the hopper. The problem is particularly severe when new or "brick" currency, which strongly tends to stick together, is being handled. Under these conditions, the contact between the picker rollers and the drum rollers generates counter-rotating contact of the picker rollers which, in turn, tends to pull the top bills in the small stack into the nip formed between the picker and drum rollers. When the bill stack is particularly small and comprises "brick" currency, the separation between the bottom and top bills is relatively small and, accordingly, the top bills are also likely to be fed in, at least partially, along with the bottom bill. The end result is a substantially high likelihood of double document and bill chaining errors.
There, accordingly, exists a distinct need in present currency feeding arrangement of the above-noted type for means for improving the "stripping" action necessary for ensuring single feeding of bills, particularly for "brick" currency, being fed from a relatively small bill stack.